The search for new adhesives having improved performance characteristics, including particularly higher bond strength, is never-ending. Another important pursuit is the discovery of new adhesives which do not require use of an organic solvent such as those employed in typical contact cements, e.g., toluene, xylene, benzene, heptane and chlorinated hydrocarbons, which present problems of atmospheric pollution, safety (e.g. flammability) and recovery costs in commercial uses.
Some adhesive studies have investigated combinations of copolymers of maleic anhydride and/or maleic acid and a plasticizer. However, such normally solid copolymers have commonly required heating to at least their melting points (generally from about 150.degree. to about 250.degree. C.) to render them soluble in the plasticizer, e.g. as disclosed in U.S. Pat. No. 4,077,935 issued Mar. 7, 1978 to W. R. Wszolek. Major disadvantages of the need for such high temperatures include higher energy requirements and unsuitability for home use or economical water-based adhesive systems.
Accordingly, there is a need for improved adhesive compositions which do not require the use of such high temperatures, and it is an object of this invention to provide such compositions. Another object is new adhesive compositions which do not require the use of organic solvents. Another object is a broad class of new adhesives characterized by unusually high bond strengths. Other objects include adhesive compositions having long shelf life, end use versatility and other desirable characteristics including convenient open times, degree of tack, etc. These and other objects of the invention will be more apparent from the following disclosure and claims in which all parts and percentages are by weight except where noted otherwise.